Nakornthab, Arm, and Surachai Chancharat. “Length of Stay and Frequency of Visits in Chiangkhan (in Thai)”. Applied Economics Journal 20, no. 2 (November 29, 2013): 23–36. Accessed May 27, 2022. https://so01.tci-thaijo.org/index.php/AEJ/article/view/14991.